Customizing automobiles has become increasingly popular among a growing population of individuals around the world. Rather than spend a lot of money on a “stock” automobile, many individuals prefer to purchase an automobile in the low to mid price range and then spend a lot of time and/or money customizing it. These customized cars and trucks are often referred to as “tuners.” The market for tuner accessories has grown exponentially in the past years. Popular accessories include spoilers, tires, rims, sound systems, seats, engine parts, custom paint, and tinting to name a few. A particularly popular target for car owners interested in individualizing their automobile is the automobile's exhaust system. Often, car owners will attempt to change the way that their automobile sounds by modifying the automobile's exhaust pipe or muffler system. Tuners often have modified exhausts to make them louder.
Making a tuner louder serves two purposes. First, to an untrained ear, a loud engine translates into the perception that the car is fast. Traditionally, speed is associated with noise. For example, race cars, motorcycles, jet aircraft, and rockets are all extremely fast, and in most cases extremely loud. And after all, driving a fast car provides a certain status for the owner in some circles. Second, making an automobile louder can enhance the driver's driving experience by allowing him or her to hear the engine over the customized sound system, enabling the driver to hear the engine as the RPMs rise and fall with each shift. Modifying an engine's exhaust system entails physically adding to or altering the stock exhaust. The modifications are structural modifications that cannot be made while driving.